附件删除与下载

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.IO;
using System.Text;

/// <summary>
///DownLoad 的摘要说明
/// </summary>
public class FileHelper
{
    public FileHelper()
    {
        //
        //TODO: 在此处添加构造函数逻辑
        //
    }
    /// <summary>
    /// 文件上传到的路径
    /// </summary>
    /// <param name="uploadPath"></param>
    public void FileUpload(string uploadPath)
    {
        try
        {
            HttpFileCollection files = HttpContext.Current.Request.Files;      //客户端上传控件集合
            for (int i = 0; i < files.Count; i++)
            {
                HttpPostedFile file = files[i];
                if (file.ContentLength > 0)
                {
                    string fileName = file.FileName;    //文件名
                    string fileType = "";               //文件类型

                    if (fileName.Length > 0)
                    {
                        fileName = fileName.Substring(fileName.LastIndexOf("\\") + 1);
                        fileType = fileName.Substring(fileName.LastIndexOf(".") + 1);
                    }
                    string uniquelyFileName = Guid.NewGuid().ToString() + "." + fileType;  //文件唯一名字
                    file.SaveAs(uploadPath + uniquelyFileName);
                    #region......保存信息到数据库

                    #endregion
                }
            }
        }
        catch (Exception ex)
        {
            HttpContext.Current.Response.Write("Error:" + ex.Message);
        }
    }
    /// <summary>
    ///  文件下载
    /// </summary>
    /// <param name="filePath">完整路径包含文件名</param>
    /// <param name="fileName">下载后的文件名包含后缀名</param>
    public void DownLoadEvent(string filePath, string fileName)
    {

        try
        {
            string browser = HttpContext.Current.Request.UserAgent.ToUpper();
            string outputFileName = "";
            FileStream fileStream = new FileStream(filePath, FileMode.Open);
            long fileSize = fileStream.Length;
            HttpContext.Current.Response.ContentType = "application/octet-stream";
            if (browser.Contains("MS") == true && browser.Contains("IE") == true)  //ie浏览器
            {
                outputFileName = HttpUtility.UrlEncode(fileName);
            }
            else if (browser.Contains("FIREFOX") == true)    //firefox浏览器
            {
                //outputFileName = "/" + fileName + "/";
                outputFileName = fileName;
            }
            else  //其他浏览器
            {
                outputFileName = HttpUtility.UrlEncode(fileName);
            }
            HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment; filename=" + outputFileName);
            HttpContext.Current.Response.AddHeader("Content-Length", fileSize.ToString());

            byte[] fileBuffer = new byte[fileSize];
            fileStream.Read(fileBuffer, 0, (int)fileSize);
            HttpContext.Current.Response.BinaryWrite(fileBuffer);

            fileStream.Dispose();
            fileStream.Flush();
            fileStream.Close();
        }
        catch (Exception ex)
        {
            HttpContext.Current.Response.Write("Error:" + ex.Message);
        }
    }
}

=============================================================

调用方法

/// <summary>
    /// 下载
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    protected void DownLoadEvent(object sender, EventArgs e)
    {
        string str = e.CommandArgument.ToString();
        fileHelper.DownLoadEvent(Server.MapPath("file/新建文本文档.txt"), "新建文本文档.txt");
    }
    /// <summary>
    /// 上传
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    protected void FileUploadEvent(object sender, EventArgs e)
    {
        fileHelper.FileUpload(Server.MapPath("File\\"));
    }